Structural and biochemical analysis of Sec translocon machinery

蛋白质跨膜运输是所有生物体中基本和必要的细胞活动之一。我们解决了膜组分SecDF的第一个三维结构，它在细菌中新合成的蛋白质在膜上的有效易位中起着重要作用。从结构特征和功能分析来看，我们提出SecDF作为一种膜整合的伴侣，它驱动蛋白质的运动，而不使用主要的能量货币ATP，但具有显着的构象变化周期，由质子H+离子（H+离子）跨膜梯度驱动。我们的SecDF函数模型已经通过一系列生化和生物物理方法得到验证。这项研究揭示了一个新的，原子水平的原理，它是细胞蛋白质传递系统的基础，特别是主动运输的生物机制，细胞不仅可以获得或处理大分子，还可以获得离子，药物和营养物质。

Transport of proteins across membranes is one of the fundamental and essential cellular activities in all organisms. We solved the first 3D structure of a membrane component SecDF, which plays an important role in efficient translocation of newly synthesized proteins across the membrane in bacteria. From the structural features and functional analyses, we proposed that SecDF functions as a membrane-integrated chaperone, which drives movement of proteins without using a major currency, ATP, of energy, but with remarkable cycles of conformational changes, powered by a proton H+ion) gradient across the membrane. Our model of the SecDF function has been verified by a series of biochemical and biophysical approaches. This research uncovers a new, atomic-level principle that underlies the cellular protein delivery systems in particular and biological mechanisms of active transport in general, by which cells acquire or dispose not only macromolecules but also ions, drugs and nutrients.